(Adapted from the Applicant's Abstract) The Comprehensive Sickle Cell Center is now in its night year of operation. In the past nine years the investigators and their colleagues have been witness to real progress in the management of sickle cell diseases (SCD). For the first time there are therapeutic options available to some patients: The overall outcome for children with sickle cell disease born and resident in the United States has never been better. However, the fundamental problems of sickle cell disease have not been solved. Many patients in the United States and elsewhere still can only expect lives full of pain and illness and ultimately death at a relatively early age. The overall goal of this Center is to seek new information while applying acquired knowledge to the full benefit of the patient. To accomplish this goal the investigators propose interrelated laboratory research projects that may lead to more efficient methods of gene therapy or the development of effective anti- sickling agents. The investigators will test therapeutic agents on a more realistic transgenic mouse model for sickle cell disease and be able to evaluate the results with sophisticated image analyses systems. In the clinical projects, the investigators seek to improve the nutritional and growth status of children with sickle cell disease in clinical trials using zinc and calcium and in a behavioral modification program to increase caloric intake. The investigators propose a long-term toxicity study of hydroxyurea therapy in children as continuation of the current Phase II study. In the era of cost-conscious health care, the investigators evaluate the economic impact of a practice change in the management of the febrile child with sickle cell disease. The investigators consolidate the education programs into one three-part project that addresses professional education in sickle cell disease as well as evaluate a formal program of transition of older adolescents to adult services. In the testing and counseling area, the investigators have adopted the high technology microchip technology to the diagnosis of sickle cell disease at the single cell level. And, the investigators develop a model of culturally sensitive genetic counseling program in a newborn screening project in a developing country.